A vegetation concrete and a method for producing the same

Abstract

This invention discloses a planted concrete and its preparation method. The planted concrete of this invention comprises a porous concrete matrix and a water-retaining functional layer. The water-retaining functional layer is attached to the inner wall of the pores in the porous concrete matrix. The water-retaining functional layer comprises cement, water-retaining filler, and cellulose ether. The preparation method of the planted concrete of this invention includes the following steps: 1) preparing a porous concrete matrix; 2) forming a water-retaining functional layer on the inner wall of the pores in the porous concrete matrix, thereby obtaining the planted concrete. The planted concrete of this invention has advantages such as excellent water retention / slow-release properties and high mechanical strength. Furthermore, its preparation process is simple and its production cost is low, making it suitable for slope protection and revegetation projects in arid environments.

Description

Technical Field

[0001] This invention relates to the field of concrete materials technology, specifically to a type of plant-based concrete and its preparation method. Background Technology

[0002] Vegetated concrete is a type of concrete with a porous structure and interconnected pores, exhibiting good air and water permeability. It not only protects slopes and prevents soil erosion but also enables the growth of plants and aquatic organisms, thereby achieving the requirements of greening slopes, improving the ecological environment and enhancing the landscape. In addition, it can also purify water and prevent water pollution.

[0003] Vegetated concrete, as a carrier for plant growth, typically contains the nutrients needed for plant growth, providing nourishment before the plant roots penetrate deep into the soil. However, traditional vegetated concrete has poor water and fertilizer retention, failing to meet the long-term water and nutrient requirements of plants. In engineering applications in arid regions, plants grown in this concrete are prone to premature wilting and death due to lack of water and nutrients. Currently, there are two main methods to improve the water retention capacity of vegetated concrete: 1) Adding high water-retention fillers: High water-retention fillers require large amounts to achieve good water retention, but this also significantly reduces the mechanical strength and durability of the vegetated concrete, failing to achieve both excellent water retention and high mechanical strength; 2) Improving the pore structure of vegetated concrete: Optimizing the pore structure is limited by its own mechanical properties and significantly increases the difficulty of construction, making it impractical.

[0004] Therefore, it is of great significance to develop a type of planted concrete that combines excellent water retention / slow-release properties with high mechanical strength and a simple preparation process. Summary of the Invention

[0005] The purpose of this invention is to provide a planted concrete and its preparation method.

[0006] The technical solution adopted in this invention is:

[0007] A type of bio-concrete comprises a porous concrete matrix and a water-retaining functional layer; the water-retaining functional layer is attached to the inner wall of the pores in the porous concrete matrix; the water-retaining functional layer comprises cement, water-retaining filler, and cellulose ether.

[0008] Preferably, the thickness of the water-retaining functional layer is 1mm to 3mm.

[0009] Preferably, the mass ratio of cement, water-retaining filler, and cellulose ether in the water-retaining functional layer is 1:0.3-1.1:0.02-0.07.

[0010] Preferably, the cement in the water-retaining functional layer is silicate cement with a grade of not less than 42.5.

[0011] Preferably, the water-retaining filler in the water-retaining functional layer is at least one of biochar powder, hydrogel, ceramic sand, pumice powder, and zeolite powder.

[0012] More preferably, the water-retaining filler in the water-retaining functional layer is composed of biochar powder and hydrogel. The hydrogel not only possesses excellent water-retaining properties, but also, when mixed with biochar powder, can absorb fertilizers and pesticides and slowly release them to increase fertilizer and pesticide efficacy.

[0013] More preferably, the water-retaining filler in the water-retaining functional layer is composed of biochar powder and hydrogel in a mass ratio of 1:1 to 3.

[0014] Preferably, the biochar powder has a particle size of 0.2 mm to 1 mm and a porosity of 70% to 80%.

[0015] Preferably, the number-average molecular weight of the cellulose ether in the water-retaining functional layer is 10,000 to 180,000, and the viscosity is 1,000 mPa·s to 40,000 mPa·s.

[0016] Preferably, the cellulose ether in the water-retaining functional layer is hydroxypropyl methylcellulose.

[0017] Preferably, the porous concrete matrix comprises cement, aggregate, admixtures, and water-reducing agent.

[0018] Preferably, the mass ratio of cement, aggregate, admixture and water-reducing agent in the porous concrete matrix is ​​1:4~6:0.1~0.3:0.01~0.03.

[0019] Preferably, the cement in the porous concrete matrix is ​​silicate cement with a grade of not less than 42.5.

[0020] Preferably, the aggregate in the porous concrete matrix has a particle size of 13.2 mm to 32.4 mm.

[0021] More preferably, the aggregate in the porous concrete matrix has a particle size of 16.5 mm to 23.4 mm.

[0022] Preferably, the admixture in the porous concrete matrix is ​​at least one of granulated blast furnace slag and silica fume.

[0023] Preferably, the strength grade of the vegetation concrete is C10 to C20, the permeability coefficient is >5mm / s, and the water retention rate is >15%.

[0024] A method for preparing vegetation concrete as described above includes the following steps:

[0025] 1) Cement, aggregates, admixtures and water-reducing agents are dispersed in water and then molded to obtain a porous concrete matrix;

[0026] 2) Cement, water-retaining filler and cellulose ether are dispersed in water to prepare a water-retaining slurry. The water-retaining slurry is then poured into the pores of a porous concrete matrix to harden and form a water-retaining functional layer, thus obtaining the planted concrete.

[0027] The beneficial effects of the present invention are: the vegetation concrete of the present invention has the advantages of excellent water retention / slow release performance and high mechanical strength, and its preparation process is simple and the production cost is low, making it suitable for slope protection and greening projects in arid environments.

[0028] Specifically:

[0029] 1) The composition of the vegetation concrete of the present invention includes a porous concrete matrix and a water-retaining functional layer. The porous concrete matrix can give the vegetation concrete high mechanical strength, while the water-retaining functional layer can give the vegetation concrete excellent water retention / slow release performance.

[0030] 2) The vegetation concrete of the present invention can control the thickness and performance of the water-retaining functional layer by adjusting the composition of the water-retaining functional slurry and the injection process parameters, thereby obtaining vegetation concrete with different permeation rates and water retention rates.

[0031] 3) After the planted concrete of the present invention is saturated with water, the water release period can reach 3 to 4 months and the nutrient release period can reach 6 to 8 months. This effectively extends the supply period of water and nutrients required for plant growth, greatly improves the utilization rate of artificial fertilization, water replenishment or rainfall, and thus effectively solves the problem of premature drying and death of plants in arid areas due to insufficient water and nutrients. Detailed Implementation

[0032] The present invention will be further explained and described below with reference to specific embodiments.

[0033] Example 1:

[0034] A type of raw concrete (strength design grade C10) is prepared by the following method:

[0035] 1) Add 1690 kg of crushed stone (aggregate) with a particle size of 16.5 mm to 23.4 mm and 40 kg of water to a mixer and mix for 30 seconds. Then add 185 kg of P.II 42.5 silicate cement, 30 kg of water, 45 kg of silica fume and 2.5 kg of polycarboxylate superplasticizer (Foshan Xinqi Tuoda New Material Group Co., Ltd.) and mix for 60 seconds. Then add 185 kg of P.II 42.5 silicate cement, 30 kg of water, 45 kg of silica fume and 2.5 kg of polycarboxylate superplasticizer (Foshan Xinqi Tuoda New Material Group Co., Ltd.) and mix for 120 seconds. Then pour into a mold for molding to obtain a porous concrete matrix.

[0036] 2) Mix 70 kg of P.II42.5 silicate cement, 10 kg of biochar powder (particle size 0.2 mm to 1 mm, porosity 70% to 80%), 30 kg of hydrogel (SPKB from Zhongshan Saipu Technology Co., Ltd., 5 mesh to 10 mesh), 3 kg of hydroxypropyl methylcellulose (number average molecular weight 180,000, viscosity 40,000 mPa·s) and 80 kg of water and stir evenly to make a water-retaining slurry. Then pour the water-retaining slurry into the pores of the porous concrete matrix to harden and form a water-retaining functional layer (thickness 1.2 mm to 2.6 mm). Then demold and cure according to "GB / T 50081-2002 Standard for Test Methods of Mechanical Properties of Ordinary Concrete" to obtain the planted concrete.

[0037] Example 2:

[0038] A type of raw concrete (strength design grade C10) is prepared by the following method:

[0039] 1) Add 1690 kg of crushed stone with a particle size of 16.5 mm to 23.4 mm and 40 kg of water to a mixer and mix for 30 seconds. Then add 185 kg of P.II 42.5 silicate cement, 30 kg of water, 45 kg of silica fume and 2.5 kg of polycarboxylate superplasticizer (Foshan Xinqi Tuoda New Material Group Co., Ltd.) and mix for 60 seconds. Then add 185 kg of P.II 42.5 silicate cement, 30 kg of water, 45 kg of silica fume and 2.5 kg of polycarboxylate superplasticizer (Foshan Xinqi Tuoda New Material Group Co., Ltd.) and mix for 120 seconds. Then pour into a mold for molding to obtain a porous concrete matrix.

[0040] 2) Mix 50 kg of P.II42.5 silicate cement, 20 kg of biochar powder (particle size 0.2 mm to 1 mm, porosity 70% to 80%), 30 kg of hydrogel (SPKB from Zhongshan Saipu Technology Co., Ltd., 5 mesh to 10 mesh), 3 kg of hydroxypropyl methylcellulose (number average molecular weight 180,000, viscosity 40,000 mPa·s) and 80 kg of water and stir evenly to make a water-retaining slurry. Then pour the water-retaining slurry into the pores of the porous concrete matrix to harden and form a water-retaining functional layer (thickness 1.0 mm to 3.0 mm). Then demold and cure according to "GB / T 50081-2002 Standard for Test Methods of Mechanical Properties of Ordinary Concrete" to obtain the planted concrete.

[0041] Example 3:

[0042] A type of raw concrete (strength design grade C10) is prepared by the following method:

[0043] 1) Add 1690 kg of crushed stone with a particle size of 16.5 mm to 23.4 mm and 40 kg of water to a mixer and mix for 30 seconds. Then add 185 kg of P.II 42.5 silicate cement, 30 kg of water, 45 kg of silica fume and 2.5 kg of polycarboxylate superplasticizer (Foshan Xinqi Tuoda New Material Group Co., Ltd.) and mix for 60 seconds. Then add 185 kg of P.II 42.5 silicate cement, 30 kg of water, 45 kg of silica fume and 2.5 kg of polycarboxylate superplasticizer (Foshan Xinqi Tuoda New Material Group Co., Ltd.) and mix for 120 seconds. Then pour into a mold for molding to obtain a porous concrete matrix.

[0044] 2) Mix 50 kg of P.Ⅱ42.5 silicate cement, 20 kg of biochar powder (particle size 0.2 mm to 1 mm, porosity 70% to 80%), 20 kg of hydrogel (SPKB from Zhongshan Saipu Technology Co., Ltd., 5 mesh to 10 mesh), 3 kg of hydroxypropyl methylcellulose (number average molecular weight 180,000, viscosity 40,000 mPa·s) and 80 kg of water and stir evenly to make a water-retaining slurry. Then pour the water-retaining slurry into the pores of the porous concrete matrix to harden and form a water-retaining functional layer (thickness 1.4 mm to 2.5 mm). Then demold and cure according to "GB / T 50081-2002 Standard for Test Methods of Mechanical Properties of Ordinary Concrete" to obtain the planted concrete.

[0045] Comparative Example 1:

[0046] A type of raw concrete (strength design grade C10) is prepared by the following method:

[0047] Add 1690 kg of crushed stone with a particle size of 16.5 mm to 23.4 mm and 40 kg of water to a mixer and mix for 30 seconds. Then add 185 kg of P.II 42.5 silicate cement, 30 kg of water, 45 kg of silica fume, and 2.5 kg of polycarboxylate superplasticizer (Foshan Xinqi Tuoda New Material Group Co., Ltd.) and mix for 60 seconds. Then add 185 kg of P.II 42.5 silicate cement, 30 kg of water, 45 kg of silica fume, and 2.5 kg of polycarboxylate superplasticizer (Foshan Xinqi Tuoda New Material Group Co., Ltd.) and mix for 120 seconds. Pour the mixture into a mold for molding, and then demold and cure it according to "GB / T 50081-2002 Standard for Test Methods of Mechanical Properties of Ordinary Concrete" to obtain the planted concrete.

[0048] Comparative Example 2:

[0049] A type of raw concrete (strength design grade C10) is prepared by the following method:

[0050] Add 1690 kg of crushed stone with a particle size of 16.5 mm to 23.4 mm and 40 kg of water to a mixer and mix for 30 seconds. Then add 185 kg of P.Ⅱ42.5 silicate cement, 30 kg of water, 45 kg of silica fume, 2.5 kg of polycarboxylate superplasticizer (Foshan Xinqi Tuoda New Material Group Co., Ltd.), 5 kg of biochar powder (particle size of 0.2 mm to 1 mm, porosity of 70% to 80%), 15 kg of hydrogel (SPKB of Zhongshan Saipu Technology Co., Ltd., 5 mesh to 10 mesh), and 1.5 kg of hydroxypropyl methylcellulose (number average molecular weight of 180,000, viscosity of 40,000 mPa·s) and mix for 120 seconds. Pour the mixture into a mold for molding, and then demold and cure it according to "GB / T 50081-2002 Standard for Test Methods of Mechanical Properties of Ordinary Concrete" to obtain the planted concrete.

[0051] Performance testing:

[0052] The performance test results of the vegetation concrete in Examples 1-3 and Comparative Examples 1-2 are shown in the table below:

[0053] Table 1 Performance test results of vegetation concrete

[0054] Water retention rate (%) 15.02 18.63 20.78 5.54 14.45 Permeability coefficient (mm / s) 6.68 5.98 5.34 8.98 9.06 Compressive strength / 28 days (MPa) 13.17 14.90 13.21 12.98 8.92 Germination rate / 28 days of natural growth (%) 93.6 94.5 94.7 85.6 90.6 Moisture release cycle (days) 96 102 108 30 92 Nutrient release cycle (days) 198 214 229 66 201

[0055] Note:

[0056] Water retention rate: The planted concrete was cut into three test samples with dimensions of 100mm×100mm×60mm. The specific gravity method was used to test the water retention rate in an environment with an air temperature of 20℃ and a relative humidity of 50%. The specific test procedure was as follows: 1) The test samples were dried and weighed, and the weight was recorded as m. dry(Unit: kg) After the test sample has cooled naturally, place it in a glass container, then place it together in a sealed vacuum chamber. Start the pressure pump until the pressure inside the vacuum chamber reaches 20 mbar, and maintain the pressure for 4 hours (to extract all the gas from the pores of the test sample); 2) Slowly inject distilled water at 20°C into the vacuum chamber until it submerges the sample by 5 cm, then stop injecting water and maintain this for 24 hours (under the pressure difference between the inside and outside, water can fully penetrate the interior of the test sample, so that all the open pores of the test sample are completely filled with water); 3) Remove the test sample from the water and wipe off the surface water, then weigh it again in the air and record the weight as m. wet (Unit: kg) Then calculate the water retention rate (i.e., water absorption rate) using the following formula: Water retention rate (%) = (m³ / kg) wet -m dry ) / m dry ×100%; 4) Replace the test sample and repeat the above operation. The arithmetic mean of the three parallel test results is taken as the water retention rate of the specimen.

[0057] Permeability coefficient: The vegetation concrete was cut into three test samples of 100mm × 100mm × 100mm size. Measurements were taken using a constant water level difference method. The water temperature during the test was 15℃. The permeability coefficient tester is based on Darcy's law. The formula for calculating the permeability coefficient at a water temperature of T℃ is: k T =QL / AHt, where k T Let T represent the permeability coefficient of the test sample at a water temperature of T℃ (in mm / s), and Q represent the amount of water that seeps out within time t (in mm). 3 L is the thickness of the test sample (in mm), and A is the bottom area of ​​the test sample (in mm²). 2 H is the water level difference (in mm), and t is the test time (in seconds). Before determining the permeability coefficient of the test sample, the test sample needs to be sealed: 1) Measure the side length of the test sample with a steel ruler, accurate to 1 mm, and calculate the area of ​​the bottom surface of the test sample; 2) Seal the sides of the test sample with waterproof sealing tape, so that it can only permeate from the pouring surface and the bottom surface, ensuring that the sides do not leak; 3) Put rubber pads on the upper and lower surfaces of the test sample to further seal its edges. Then, test the permeability coefficient of the test sample according to the following steps: 1) Place the treated test sample on the sample stage of the permeability coefficient tester, slowly raise the sample stage, and firmly fix the test sample; 2) Start the submersible pump to introduce circulating water into the test device, and discharge the water above the overflow port through the overflow pipe; 3) After the water level difference stabilizes, activate the test button on the operation panel, and read the test result on the operation panel after the test is completed;

[0058] 4) Replace the test sample and repeat the above operation. Use the arithmetic mean of the three parallel test results as the permeability coefficient of the test sample.

[0059] Compressive strength / 28 days: Tested according to "GB / T 50081-2002 Standard for Test Methods of Mechanical Properties of Ordinary Concrete", with a sample size of 100mm×100mm×100mm.

[0060] Germination rate / 28 days of natural growth: Tall fescue seeds were placed in the internal holes of the test sample and then placed naturally for 28 days at a temperature of 20℃ and a relative humidity of 70%. The number of seeds that germinated normally was counted, and the germination rate was calculated according to the following formula: Germination rate (%) = Number of normally germinated seeds / Number of test seeds × 100%. Specific testing process: 1) Prepare tall fescue seed samples and record the number of seeds to ensure the samples are representative. Place the tall fescue seeds evenly on a paper towel, cover them with another paper towel, moisten the paper towel, seal it in a plastic bag, and store it in a dark place at room temperature for 24 hours to restore seed viability; 2) Place the tall fescue seeds into the internal holes of a planting concrete containing nutrient soil. The nutrient substrate consists of 65% fertile garden soil, 10% fine sand, and 25% burnt soil. Sift the soil, add 0.4% calcium magnesium phosphate fertilizer and appropriate amount of water, and mix well; 3) Under the conditions of 20℃ and 70% relative humidity, place the planting concrete in a suitable location, avoiding direct sunlight or excessive wind. At the same time, check the seeds in the holes for germination once a day; 4) After 28 days, count the number of normally germinated seeds in the container. The standard for normal germination is that the length of the new shoot is more than half the length of the seed itself.

[0061] Water release cycle and nutrient release cycle: The test was conducted in accordance with "HG / T 4216-2011 Rapid Detection Method for Nutrient Release Period and Release Rate of Slow-Release and Controlled-Release Fertilizers".

[0062] As shown in Table 1:

[0063] a) The compressive strength of the vegetated concrete in Examples 1-3 and Comparative Examples 1-2 was 8.92 MPa to 14.90 MPa after 28 days. The compressive strength of the vegetated concrete in Comparative Example 2 did not meet the corresponding design requirements, indicating that adding water-retaining filler directly to cement to prepare vegetated concrete can easily lead to a decrease in strength. The permeability coefficient of the vegetated concrete in Examples 1-3 and Comparative Examples 1-2 was greater than 5 mm / s, which met the requirements for the permeability coefficient of permeable pavement.

[0064] b) Under simulated drought conditions, compared with the permeable concrete of Comparative Example 1, the germination rate of tall fescue increased by 9.34%, 10.40% and 10.63% respectively in the vegetated concrete of Examples 1-3, indicating that the water retention performance of the water-retaining filler is conducive to the germination and growth of tall fescue, and the number of plants that survive is also relatively large.

[0065] c) The vegetation concrete of Examples 1 to 3 has a water release period of 3 to 4 months and a nutrient release period of 6 to 8 months after saturation water absorption. This effectively extends the supply period of water and nutrients required for plant growth, greatly improves the utilization rate of artificial fertilization, water replenishment or rainfall, and thus effectively solves the problem of premature drying and death of plants in arid areas due to insufficient water and nutrients.

[0066] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A type of bio-concrete, characterized in that, The composition includes a porous concrete matrix and a water-retaining functional layer; the water-retaining functional layer is attached to the inner wall of the pores in the porous concrete matrix; the water-retaining functional layer is composed of cement, water-retaining filler, and cellulose ether; the mass ratio of cement, water-retaining filler, and cellulose ether in the water-retaining functional layer is 1:0.3-1.1:0.02-0.07; the water-retaining filler in the water-retaining functional layer is composed of biochar powder and hydrogel; the particle size of the biochar powder is 0.2mm-1mm, and the porosity is 70%-80%; the thickness of the water-retaining functional layer is 1mm-3mm; after the planted concrete is saturated with water, the water release period can reach 3-4 months, and the nutrient release period can reach 6-8 months.

2. The vegetation concrete according to claim 1, characterized in that: The cement in the water-retaining functional layer is silicate cement with a grade of not less than 42.

5.

3. The vegetation concrete according to claim 1 or 2, characterized in that: The porous concrete matrix comprises cement, aggregate, admixtures, and water-reducing agent.

4. The vegetation concrete according to claim 3, characterized in that: The mass ratio of cement, aggregate, admixture, and water-reducing agent in the porous concrete matrix is ​​1:4~6:0.1~0.3:0.01~0.

03.

5. The vegetation concrete according to claim 3, characterized in that: The cement in the porous concrete matrix is ​​silicate cement with a grade of not less than 42.

5.

6. The vegetation concrete according to claim 3, characterized in that: The aggregate in the porous concrete matrix has a particle size of 13.2 mm to 32.4 mm; the admixture in the porous concrete matrix is ​​at least one of granulated blast furnace slag and silica fume.

7. A method for preparing vegetation concrete as described in any one of claims 3 to 6, characterized in that, Includes the following steps: 1) Cement, aggregates, admixtures and water-reducing agents are dispersed in water and then molded to obtain a porous concrete matrix; 2) Cement, water-retaining filler and cellulose ether are dispersed in water to prepare a water-retaining slurry. The water-retaining slurry is then poured into the pores of a porous concrete matrix to harden and form a water-retaining functional layer, thus obtaining the planted concrete.